Acterna,
Agilent Tecgnologies ,
Ando,
Anritsu Wiltron,
Consultronics ,
CTCU ,
Digital Lightwave,
IDS ,
IFR (Marconi Inst.),
INET,
RAD,
Radcom ,
Sunrise ,
Tektronix ,
Tekelec-Temex ,
Trend
Some communications lists to start with are analysys.co
and the ATM Forum.
Official data is available from the ITU ,
ETSI , T1X1
John Scourias has a good set of Telecommunication links but avoid his Home Page if your link is slow.
The Broadband Telephony Buyers Guide
SOME COMPANIES INVOLVED IN COMMUNICATIONS TEST :
Acterna,
Agilent Tecgnologies ,
Ando,
Anritsu Wiltron,
Consultronics ,
CTCU ,
Digital Lightwave,
IDS ,
IFR (Marconi Inst.),
INET,
RAD,
Radcom ,
Sunrise ,
Tektronix ,
Tekelec-Temex ,
Trend
MOBILE COMMUNICATION :
John Scourias also has some information on GSM.
Some companies involved with GSM are Nokia , Ericsson , Cellnet , and Orange .